Method and apparatus for transmitting and receiving radio signals in a wireless communication system

ABSTRACT

The present invention relates to a wireless communication system, and more particularly, to a method of transmitting and receiving a radio signal and an apparatus therefor. The method comprises the steps of receiving data in a time unit #n of a first frequency band and transmitting A/N in a time unit #m+k of a second frequency band in response to the data. In this case, the first frequency band and the second frequency band have different subcarrier spacing and a time unit #m of the second frequency band indicates the last time unit among a plurality of time units of the second frequency band corresponding to the time unit #n of the first frequency band.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.17/989,308, filed on Nov. 17, 2022, which is a continuation of U.S.application Ser. No. 17/512,220, filed on Oct. 27, 2021, now U.S. Pat.No. 11,627,577, which is a continuation of U.S. application Ser. No.16/065,698, filed on Jan. 10, 2019, now U.S. Pat. No. 11,219,023, whichis a National Stage application under 35 U.S.C. § 371 of InternationalApplication No. PCT/KR2018/006855, filed on Jun. 18, 2018, which claimsthe benefit of Korean Application No. 10-2018-0039476, filed on Apr. 5,2018, U.S. Provisional Application No. 62/630,324, filed on Feb. 14,2018, U.S. Provisional Application No. 62/548,912, filed on Aug. 22,2017, and U.S. Provisional Application No. 62/520,560, filed on Jun. 16,2017. The disclosures of the prior applications are incorporated byreference in their entirety.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly, to a method and apparatus for transmitting/receivinga wireless signal. The wireless communication system includes a CA-based(Carrier Aggregation-based) wireless communication system.

BACKGROUND

Generally, a wireless communication system is developing to diverselycover a wide range to provide such a communication service as an audiocommunication service, a data communication service and the like. Thewireless communication is a sort of a multiple access system capable ofsupporting communications with multiple users by sharing availablesystem resources (e.g., bandwidth, transmit power, etc.). For example,the multiple access system may include one of CDMA (code divisionmultiple access) system, FDMA (frequency division multiple access)system, TDMA (time division multiple access) system, OFDMA (orthogonalfrequency division multiple access) system, SC-FDMA (single carrierfrequency division multiple access) system and the like.

SUMMARY

An object of the present invention is to provide a method of efficientlytransmitting/receiving control information in a wireless communicationand an apparatus therefor.

Technical tasks obtainable from the present invention are non-limitedthe abovementioned technical task. And, other unmentioned technicaltasks can be clearly understood from the following description by thosehaving ordinary skill in the technical field to which the presentinvention pertains.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, accordingto one embodiment, a method of performing communication by a userequipment in a wireless communication system is provided, wherein themethod includes: receiving data in a time unit #n of a first frequencyband, and transmitting A/N (Acknowledgement/Negative acknowledgement)for the data in a time unit #m+k of a second frequency band. In thiscase, subcarrier spacing of the first frequency band is different fromsubcarrier spacing of the second frequency band and a time unit #m ofthe second frequency band indicates the last time unit among a pluralityof time units of the second frequency band corresponding to the timeunit #n of the first frequency band.

To further achieve these and other advantages and in accordance with thepurpose of the present invention, according to a different embodiment, auser equipment for use in a wireless communication system is provided,wherein the user equipment includes: an RF (Radio Frequency) module, anda processor, the processor configured to receive data in a time unit #nof a first frequency band, the processor configured to transmit A/N(Acknowledgement/Negative acknowledgement) for the data in a time unit#m+k of a second frequency band. In this case, subcarrier spacing of thefirst frequency band is different from subcarrier spacing of the secondfrequency band and a time unit #m of the second frequency band indicatesthe last time unit among a plurality of time units of the secondfrequency band corresponding to the time unit #n of the first frequencyband.

To further achieve these and other advantages and in accordance with thepurpose of the present invention, according to a further differentembodiment, a method of performing communication by a base station in awireless communication system is provided, wherein the base stationincludes: receiving data in a time unit #n of a first frequency band andtransmitting A/N (Acknowledgement/Negative acknowledgement) for the datain a time unit #m+k of a second frequency band in response to the data.In this case, subcarrier spacing of the first frequency band isdifferent from subcarrier spacing of the second frequency band and atime unit #m of the second frequency band indicates the last time unitamong a plurality of time units of the second frequency bandcorresponding to the time unit #n of the first frequency band.

To further achieve these and other advantages and in accordance with thepurpose of the present invention, according to a further differentembodiment, a base station for use in a wireless communication system isprovided, wherein the base station includes: an RF (Radio Frequency)module and a processor, the processor configured to transmit data in atime unit #n of a first frequency band, the processor configured toreceive A/N (Acknowledgement/Negative acknowledgement) for the data in atime unit #m+k of a second frequency band. In this case, subcarrierspacing of the first frequency band is different from subcarrier spacingof the second frequency band and a time unit #m of the second frequencyband indicates the last time unit among a plurality of time units of thesecond frequency band corresponding to the time unit #n of the firstfrequency band.

Preferably, each time unit includes the same number of OFDM (orthogonalfrequency division multiplexing)-based symbols and a length of each timeunit can be determined based on subcarrier spacing.

Preferably, the subcarrier spacing of the first frequency band may besmaller than the subcarrier spacing of the second frequency band.

Preferably, information on the k can be received via a control channelthat schedules the data.

Preferably, the first frequency band corresponds to a Scell (Secondarycell) and the second frequency band may correspond to a cell configuredto transmit a PUCCH (Physical Uplink Control Channel).

Preferably, the data is received via PDSCH (Physical Downlink SharedChannel) and the A/N can be transmitted via PUCCH (Physical uplinkControl Channel).

Preferably, the wireless communication system may include 3GPP (3rdGeneration Partnership Project)-based wireless communication system.

According to the present invention, wireless signal transmission andreception can be efficiently performed in a wireless communicationsystem.

Effects obtainable from the present invention may be non-limited by theabove mentioned effect. And, other unmentioned effects can be clearlyunderstood from the following description by those having ordinary skillin the technical field to which the present invention pertains.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 illustrates physical channels used in 3GPP LTE(-A) and a signaltransmission method using the same;

FIGS. 2A and 2B illustrate a radio frame structure;

FIG. 3 illustrates a resource grid of a downlink slot;

FIG. 4 illustrates a downlink subframe structure;

FIG. 5 illustrates the structure of an uplink subframe used in LTE(-A);

FIG. 6 illustrates Single Carrier Frequency Division Multiple Access(SC-FDMA) scheme and Orthogonal Frequency Division Multiple Access(OFDMA) scheme;

FIG. 7 illustrates UL HARQ (Uplink Hybrid Automatic Repeat reQuest)operation;

FIG. 8 illustrates a carrier aggregation (CA)-based wirelesscommunication system;

FIG. 9 illustrates cross-carrier scheduling;

FIG. 10 illustrates a structure of a self-contained subframe;

FIG. 11 illustrates a frame structure defined in 3GPP NR;

FIGS. 12 to 16 illustrate signal transmission according to the presentinvention;

FIG. 17 illustrates a base station and a user equipment applicable to anembodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention are applicable to a variety ofwireless access technologies such as code division multiple access(CDMA), frequency division multiple access (FDMA), time divisionmultiple access (TDMA), orthogonal frequency division multiple access(OFDMA), and single carrier frequency division multiple access(SC-FDMA). CDMA can be implemented as a radio technology such asUniversal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can beimplemented as a radio technology such as Global System for Mobilecommunications (GSM)/General Packet Radio Service (GPRS)/Enhanced DataRates for GSM Evolution (EDGE). OFDMA can be implemented as a radiotechnology such as Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wireless Fidelity (Wi-Fi)), IEEE 802.16 (Worldwideinteroperability for Microwave Access (WiMAX)), IEEE 802.20, and EvolvedUTRA (E-UTRA). UTRA is a part of Universal Mobile TelecommunicationsSystem (UMTS). 3rd Generation Partnership Project (3GPP) Long TermEvolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA,employing OFDMA for downlink and SC-FDMA for uplink. LTE-Advanced(LTE-A) evolves from 3GPP LTE. While the following description is given,centering on 3GPP LTE/LTE-A for clarity, this is purely exemplary andthus should not be construed as limiting the present invention.

In a wireless communication system, a user equipment (UE) receivesinformation through downlink (DL) from a base station (BS) and transmitinformation to the BS through uplink (UL). The information transmittedand received by the BS and the UE includes data and various controlinformation and includes various physical channels according totype/usage of the information transmitted and received by the UE and theBS.

FIG. 1 illustrates physical channels used in 3GPP LTE(-A) and a signaltransmission method using the same.

When powered on or when a UE initially enters a cell, the UE performsinitial cell search involving synchronization with a BS in step S101.For initial cell search, the UE synchronizes with the BS and acquireinformation such as a cell Identifier (ID) by receiving a primarysynchronization channel (P-SCH) and a secondary synchronization channel(S-SCH) from the BS. Then the UE may receive broadcast information fromthe cell on a physical broadcast channel (PBCH). In the meantime, the UEmay check a downlink channel status by receiving a downlink referencesignal (DL RS) during initial cell search.

After initial cell search, the UE may acquire more specific systeminformation by receiving a physical downlink control channel (PDCCH) andreceiving a physical downlink shared channel (PDSCH) based oninformation of the PDCCH in step S102.

The UE may perform a random access procedure to access the BS in stepsS103 to S106. For random access, the UE may transmit a preamble to theBS on a physical random access channel (PRACH) (S103) and receive aresponse message for preamble on a PDCCH and a PDSCH corresponding tothe PDCCH (S104). In the case of contention-based random access, the UEmay perform a contention resolution procedure by further transmittingthe PRACH (S105) and receiving a PDCCH and a PDSCH corresponding to thePDCCH (S106).

After the foregoing procedure, the UE may receive a PDCCH/PDSCH (S107)and transmit a physical uplink shared channel (PUSCH)/physical uplinkcontrol channel (PUCCH) (S108), as a general downlink/uplink signaltransmission procedure. Control information transmitted from the UE tothe BS is referred to as uplink control information (UCI). The UCIincludes hybrid automatic repeat and requestacknowledgement/negative-acknowledgement (HARQ-ACK/NACK), schedulingrequest (SR), channel state information (CSI), etc. The CSI includes achannel quality indicator (CQI), a precoding matrix indicator (PMI), arank indicator (RI), etc. While the UCI is transmitted on a PUCCH ingeneral, the UCI may be transmitted on a PUSCH when control informationand traffic data need to be simultaneously transmitted. In addition, theUCI may be aperiodically transmitted through a PUSCH according torequest/command of a network.

FIGS. 2A and 2B illustrate a radio frame structure. Uplink/downlink datapacket transmission is performed on a subframe-by-subframe basis. Asubframe is defined as a predetermined time interval including aplurality of symbols. 3GPP LTE supports a type-1 radio frame structureapplicable to frequency division duplex (FDD) and a type-2 radio framestructure applicable to time division duplex (TDD).

FIG. 2A illustrates a type-1 radio frame structure. A downlink subframeincludes 10 subframes each of which includes 2 slots in the time domain.A time for transmitting a subframe is defined as a transmission timeinterval (TTI). For example, each subframe has a duration of 1 ms andeach slot has a duration of 0.5 ms. A slot includes a plurality of OFDMsymbols in the time domain and includes a plurality of resource blocks(RBs) in the frequency domain. Since downlink uses OFDM in 3GPP LTE, anOFDM symbol represents a symbol period. The OFDM symbol may be called anSC-FDMA symbol or symbol period. An RB as a resource allocation unit mayinclude a plurality of consecutive subcarriers in one slot.

The number of OFDM symbols included in one slot may depend on cyclicprefix (CP) configuration. CPs include an extended CP and a normal CP.When an OFDM symbol is configured with the normal CP, for example, thenumber of OFDM symbols included in one slot may be 7. When an OFDMsymbol is configured with the extended CP, the length of one OFDM symbolincreases, and thus the number of OFDM symbols included in one slot issmaller than that in case of the normal CP. In case of the extended CP,the number of OFDM symbols allocated to one slot may be 6. When achannel state is unstable, such as a case in which a UE moves at a highspeed, the extended CP can be used to reduce inter-symbol interference.

When the normal CP is used, one subframe includes 14 OFDM symbols sinceone slot has 7 OFDM symbols. The first three OFDM symbols at most ineach subframe can be allocated to a PDCCH and the remaining OFDM symbolscan be allocated to a PDSCH.

FIG. 2B illustrates a type-2 radio frame structure. The type-2 radioframe includes 2 half frames. Each half frame includes 4(5) normalsubframes and 10 special subframes. The normal subframes are used foruplink or downlink according to UL-DL configuration. A subframe iscomposed of 2 slots.

Table 1 shows subframe configurations in a radio frame according toUL-DL configurations.

TABLE 1 Uplink- Downlink- downlink to-Uplink config- Switch pointSubframe number uration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U UD S U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 msD S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D DD D 6 5 ms D S U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes DwPTS(Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS (Uplink PilotTimeSlot). DwPTS is used for initial cell search, synchronization orchannel estimation in a UE and UpPTS is used for channel estimation in aBS and uplink transmission synchronization in a UE. The GP eliminates ULinterference caused by multi-path delay of a DL signal between a UL anda DL.

The radio frame structure is merely exemplary and the number ofsubframes included in the radio frame, the number of slots included in asubframe, and the number of symbols included in a slot can be vary.

FIG. 3 illustrates a resource grid of a downlink slot.

Referring to FIG. 3 , a downlink slot includes a plurality of OFDMsymbols in the time domain. While one downlink slot may include 7 OFDMsymbols and one resource block (RB) may include 12 subcarriers in thefrequency domain in the figure, the present invention is not limitedthereto. Each element on the resource grid is referred to as a resourceelement (RE). One RB includes 12×7 REs. The number NRB of RBs includedin the downlink slot depends on a downlink transmit bandwidth. Thestructure of an uplink slot may be same as that of the downlink slot.

FIG. 4 illustrates a downlink subframe structure.

Referring to FIG. 4 , a maximum of three (four) OFDM symbols located ina front portion of a first slot within a subframe correspond to acontrol region to which a control channel is allocated. The remainingOFDM symbols correspond to a data region to which a physical downlinkshared chancel (PDSCH) is allocated. A basic resource unit of the dataregion is an RB. Examples of downlink control channels used in LTEinclude a physical control format indicator channel (PCFICH), a physicaldownlink control channel (PDCCH), a physical hybrid ARQ indicatorchannel (PHICH), etc. The PCFICH is transmitted at a first OFDM symbolof a subframe and carries information regarding the number of OFDMsymbols used for transmission of control channels within the subframe.The PHICH is a response of uplink transmission and carries a HARQacknowledgment (ACK)/negative-acknowledgment (NACK) signal. Controlinformation transmitted through the PDCCH is referred to as downlinkcontrol information (DCI). The DCI includes uplink or downlinkscheduling information or an uplink transmit power control command foran arbitrary UE group.

Control information transmitted through the PDCCH is referred to asdownlink control information (DCI). Formats 0, 3, 3A and 4 for uplinkand formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B and 2C for downlink are definedas DCI formats. Information field type, the number of informationfields, the number of bits of each information field, etc. depend on DICformat. For example, the DCI formats selectively include informationsuch as hopping flag, RB assignment, MCS (Modulation Coding Scheme), RV(Redundancy Version), NDI (New Data Indicator), TPC (Transmit PowerControl), HARQ process number, PMI (Precoding Matrix Indicator)confirmation as necessary. Accordingly, the size of control informationmatched to a DCI format depends on the DCI format. An arbitrary DCIformat may be used to transmit two or more types of control information.For example, DIC formats 0/1A is used to carry DCI format 0 or DICformat 1, which are discriminated from each other using a flag field.

A PDCCH may carry a transport format and a resource allocation of adownlink shared channel (DL-SCH), resource allocation information of anuplink shared channel (UL-SCH), paging information on a paging channel(PCH), system information on the DL-SCH, information on resourceallocation of an upper-layer control message such as a random accessresponse transmitted on the PDSCH, a set of Tx power control commands onindividual UEs within an arbitrary UE group, a Tx power control command,information on activation of a voice over IP (VoIP), etc. A plurality ofPDCCHs can be transmitted within a control region. The UE can monitorthe plurality of PDCCHs. The PDCCH is transmitted on an aggregation ofone or several consecutive control channel elements (CCEs). The CCE is alogical allocation unit used to provide the PDCCH with a coding ratebased on a state of a radio channel. The CCE corresponds to a pluralityof resource element groups (REGs). A format of the PDCCH and the numberof bits of the available PDCCH are determined by the number of CCEs. TheBS determines a PDCCH format according to DCI to be transmitted to theUE, and attaches a cyclic redundancy check (CRC) to control information.The CRC is masked with a unique identifier (referred to as a radionetwork temporary identifier (RNTI)) according to an owner or usage ofthe PDCCH. If the PDCCH is for a specific UE, a unique identifier (e.g.,cell-RNTI (C-RNTI)) of the UE may be masked to the CRC. Alternatively,if the PDCCH is for a paging message, a paging identifier (e.g.,paging-RNTI (P-RNTI)) may be masked to the CRC. If the PDCCH is forsystem information (more specifically, a system information block(SIB)), a system information RNTI (SI-RNTI) may be masked to the CRC.When the PDCCH is for a random access response, a random access-RNTI(RA-RNTI) may be masked to the CRC.

The PDCCH carries a message known as DCI which includes resourceassignment information and other control information for a UE or UEgroup. In general, a plurality of PDCCHs can be transmitted in asubframe. Each PDCCH is transmitted using one or more CCEs. Each CCEcorresponds to 9 sets of 4 REs. The 4 REs are referred to as an REG. 4QPSK symbols are mapped to one REG. REs allocated to a reference signalare not included in an REG, and thus the total number of REGs in OFDMsymbols depends on presence or absence of a cell-specific referencesignal. The concept of REG (i.e. group based mapping, each groupincluding 4 REs) is used for other downlink control channels (PCFICH andPHICH). That is, REG is used as a basic resource unit of a controlregion. 4 PDCCH formats are supported as shown in Table 2.

TABLE 2 PDCCH Number of Number of Number of PDCCH format CCEs (n) REGsbits 0 1 9 72 1 2 8 144 2 4 36 288 3 5 72 576

CCEs are sequentially numbered. To simplify a decoding process,transmission of a PDCCH having a format including n CCEs can be startedusing as many CCEs as a multiple of n. The number of CCEs used totransmit a specific PDCCH is determined by a BS according to channelcondition. For example, if a PDCCH is for a UE having a high-qualitydownlink channel (e.g. a channel close to the BS), only one CCE can beused for PDCCH transmission. However, for a UE having a poor channel(e.g. a channel close to a cell edge), 8 CCEs can be used for PDCCHtransmission in order to obtain sufficient robustness. In addition, apower level of the PDCCH can be controlled according to channelcondition.

LTE defines CCE positions in a limited set in which PDCCHs can bepositioned for each UE. CCE positions in a limited set that the UE needsto monitor in order to detect the PDCCH allocated thereto may bereferred to as a search space (SS). In LTE, the SS has a size dependingon PDCCH format. A UE-specific search space (USS) and a common searchspace (CSS) are separately defined. The USS is set per UE and the rangeof the CSS is signaled to all UEs. The USS and the CSS may overlap for agiven UE. In the case of a considerably small SS with respect to aspecific UE, when some CCEs positions are allocated in the SS, remainingCCEs are not present. Accordingly, the BS may not find CCE resources onwhich PDCCHs will be transmitted to available UEs within givensubframes. To minimize the possibility that this blocking continues tothe next subframe, a UE-specific hopping sequence is applied to thestarting point of the USS.

Table 3 shows sizes of the CSS and USS.

TABLE 3 Number of Number of candidates candidates in PDCCH Number of incommon dedicated format CCEs (n) search space search space 0 1 — 6 1 2 —6 2 4 4 2 3 8 2 2

To control computational load of blind decoding based on the number ofblind decoding processes to an appropriate level, the UE is not requiredto simultaneously search for all defined DCI formats. In general, the UEsearches for formats 0 and 1A at all times in the USS. Formats 0 and 1Ahave the same size and are discriminated from each other by a flag in amessage. The UE may need to receive an additional format (e.g. format 1,1B or 2 according to PDSCH transmission mode set by a BS). The UEsearches for formats 1A and 1C in the CSS. Furthermore, the UE may beset to search for format 3 or 3A. Formats 3 and 3A have the same size asthat of formats 0 and 1A and may be discriminated from each other byscrambling CRC with different (common) identifiers rather than aUE-specific identifier. PDSCH transmission schemes and informationcontent of DCI formats according to transmission mode (TM) are arrangedbelow.

Transmission Mode (TM)

-   -   Transmission mode 1: Transmission from a single base station        antenna port    -   Transmission mode 2: Transmit diversity    -   Transmission mode 3: Open-loop spatial multiplexing    -   Transmission mode 4: Closed-loop spatial multiplexing    -   Transmission mode 5: Multi-user MIMO (Multiple Input Multiple        Output)    -   Transmission mode 6: Closed-loop rank-1 precoding    -   Transmission mode 7: Single-antenna port (port5) transmission    -   Transmission mode 8: Double layer transmission (ports 7 and 8)        or single-antenna port (port 7 or 8) transmission    -   Transmission mode 9: Transmission through up to 8 layers (ports        7 to 14) or single-antenna port (port 7 or 8) transmission

DCI Format

-   -   Format 0: Resource grants for PUSCH transmission    -   Format 1: Resource assignments for single codeword PDSCH        transmission (transmission modes 1, 2 and 7)    -   Format 1A: Compact signaling of resource assignments for single        codeword PDSCH (all modes)    -   Format 1B: Compact resource assignments for PDSCH using rank-1        closed loop precoding (mod 6)    -   Format 1C: Very compact resource assignments for PDSCH (e.g.        paging/broadcast system information)    -   Format 1D: Compact resource assignments for PDSCH using        multi-user MIMO (mode 5)    -   Format 2: Resource assignments for PDSCH for closed-loop MIMO        operation (mode 4)    -   Format 2A: Resource assignments for PDSCH for open-loop MIMO        operation (mode 3)    -   Format 3/3A: Power control commands for PUCCH and PUSCH with        2-bit/1-bit power adjustments

FIG. 5 illustrates a structure of an uplink subframe used in LTE(-A).

Referring to FIG. 5 , a subframe 500 is composed of two 0.5 ms slots501. Assuming a length of a normal cyclic prefix (CP), each slot iscomposed of 7 symbols 502 and one symbol corresponds to one SC-FDMAsymbol. A resource block (RB) 503 is a resource allocation unitcorresponding to 12 subcarriers in the frequency domain and one slot inthe time domain. The structure of the uplink subframe of LTE(-A) islargely divided into a data region 504 and a control region 505. A dataregion refers to a communication resource used for transmission of datasuch as voice, a packet, etc. transmitted to each UE and includes aphysical uplink shared channel (PUSCH). A control region refers to acommunication resource for transmission of an uplink control signal, forexample, downlink channel quality report from each UE, receptionACK/NACK for a downlink signal, uplink scheduling request, etc. andincludes a physical uplink control channel (PUCCH). A sounding referencesignal (SRS) is transmitted through an SC-FDMA symbol that is lastlypositioned in the time axis in one subframe. SRSs of a plurality of UEs,which are transmitted to the last SC-FDMAs of the same subframe, can bedifferentiated according to frequency positions/sequences. The SRS isused to transmit an uplink channel state to an eNB and is periodicallytransmitted according to a subframe period/offset set by a higher layer(e.g., RRC layer) or aperiodically transmitted at the request of theeNB.

FIG. 6 illustrates SC-FDMA and OFDMA schemes. The 3GPP system employsOFDMA in downlink and uses SC-FDMA in uplink.

Referring to FIG. 6 , both a UE for transmitting an uplink signal and aBS for transmitting a downlink signal include a serial-to-parallelconverter 401, a subcarrier mapper 403, an M-point IDFT module 404, anda cyclic prefix (CP) adder 406. The UE for transmitting a signalaccording to SC-FDMA additionally includes an N-point DFT module 402.

Next, HARQ (Hybrid Automatic Repeat reQuest) will be described. Whenthere are a plurality of UEs having data to be transmitted onuplink/downlink in a wireless communication, an eNB selects UEs whichwill transmit data per transmission time internal (TTI) (e.g.,subframe). In a system using multiple carriers and the like, an eNBselects UEs which will transmit data on uplink/downlink per TTI and alsoselects a frequency band to be used for data transmission of thecorresponding UEs.

When description is based on uplink (UL), UEs transmit reference signals(or pilot signals) on uplink and an eNB detects channel states of theUEs using the reference signals transmitted from the UEs and selects UEswhich will transmit data on uplink in each unit frequency band per TTI.The eNB notifies the UEs of the result of selection. That is, the eNBtransmits, to UL scheduled UEs, a UL assignment message indicating thatthe UEs may transmit data using a specific frequency band in a specificTTI. The UL assignment message is also referred to as a UL grant. TheUEs transmit data on uplink according to the UL assignment message. TheUL assignment message may include UE identity (ID), RB allocationinformation, a modulation and coding scheme (MCS), a redundancy version(RV), new data indication (NDI) and the like.

In the case of synchronous HARQ, a retransmission time is appointed inthe system (e.g., after 4 subframes from a NACK reception time)(synchronous HARQ). Accordingly, the eNB may send a UL grant message toUEs only in initial transmission and subsequent retransmission isperformed according to an ACK/NACK signal (e.g., PHICH signal). In thecase of asynchronous HARQ, a retransmission time is not appointed andthus the eNB needs to send a retransmission request message to UEs.Further, frequency resources or an MCS for retransmission are identicalto those in previous transmission in the case of non-adaptive HARQ,whereas frequency resources or an MCS for retransmission may differ fromthose in previous transmission in the case of adaptive HARQ. Forexample, in the case of asynchronous adaptive HARQ, the retransmissionrequest message may include UE ID, RB allocation information, HARQprocess ID/number, RV and NDI information because frequency resources oran MCS for retransmission vary with transmission time.

FIG. 7 illustrates a UL HARQ operation in an LTE(-A) system. In theLTE(-A) system, asynchronous adaptive HARQ is used as UL HARQ. When8-channel HARQ is used, 0 to 7 are provided as HARQ process numbers. OneHARQ process operates per TTI (e.g., sub frame). Referring to FIG. 7 , aUL grant is transmitted to a UE 120 through a PDCCH (S600). The UE 120transmits UL data to an eNB 110 after 4 subframes from the time (e.g.,subframe 0) at which the UL grant is received using an RB and an MCSdesignated by the UL grant (S602). The eNB 110 decodes the UL datareceived from the UE 120 and then generates ACK/NACK. When decoding ofthe UL data fails, the eNB 110 transmits NACK to the UE 120 (S604). TheUE 120 retransmits the UL data after 4 subframes from the time at whichNACK is received (S606). Initial transmission and retransmission of theUL data are performed through the same HARQ process (e.g., HARQ process4). ACK/NACK information may be transmitted through a PHICH.

FIG. 8 illustrates carrier aggregation (CA) communication system.

Referring to FIG. 8 , a plurality of UL/DL component carriers (CCs) canbe aggregated to support a wider UL/DL bandwidth. The CCs may becontiguous or non-contiguous in the frequency domain. Bandwidths of theCCs can be independently determined. Asymmetrical CA in which the numberof UL CCs is different from the number of DL CCs can be implemented.Control information may be transmitted/received only through a specificCC. This specific CC may be referred to as a primary CC and other CCsmay be referred to as secondary CCs. For example, when cross-carrierscheduling (or cross-CC scheduling) is applied, a PDCCH for downlinkallocation can be transmitted on DL CC #0 and a PDSCH correspondingthereto can be transmitted on DL CC #2. The term “component carrier” maybe replaced by other equivalent terms (e.g. “carrier”, “cell”, etc.).

For cross-CC scheduling, a carrier indicator field (CIF) is used.Presence or absence of the CIF in a PDCCH can be determined by higherlayer signaling (e.g. RRC signaling) semi-statically and UE-specifically(or UE group-specifically). The baseline of PDCCH transmission issummarized as follows.

-   -   CIF disabled: a PDCCH on a DL CC is used to allocate a PDSCH        resource on the same DL CC or a PUSCH resource on a linked UL        CC.    -   No CIF    -   CIF enabled: a PDCCH on a DL CC can be used to allocate a PDSCH        or PUSCH resource on a specific DL/UL CC from among a plurality        of aggregated DL/UL CCs using the CIF.    -   LTE DCI format extended to have CIF    -   CIF corresponds to a fixed x-bit field (e.g. x=3) (when CIF is        set)    -   CIF position is fixed irrespective of DIC format size (when CIF        is set)

When the CIF is present, the BS may allocate a monitoring DL CC (set) toreduce BD complexity of the UE. For PDSCH/PUSCH scheduling, the UE maydetect/decode a PDCCH only on the corresponding DL CCs. The BS maytransmit the PDCCH only through the monitoring DL CC (set). Themonitoring DL CC set may be set UE-specifically, UE-group-specificallyor cell-specifically.

FIG. 9 illustrates scheduling when a plurality of carriers isaggregated. It is assumed that 3 DL CCs are aggregated and DL CC A isset to a PDCCH CC. DL CC A-C may be referred to as a serving CC, servingcarrier, serving cell, etc. When the CIF is disabled, each DL CC cantransmit only a PDCCH that schedules a PDSCH corresponding to the DL CCwithout a CIF according to LTE PDCCH rule (non-cross-CC scheduling).When the CIF is enabled through UE-specific (or UE-group-specific orcell-specific) higher layer signaling, a specific CC (e.g. DL CC A) cantransmit not only the PDCCH that schedules the PDSCH of DL CC A but alsoPDCCHs that schedule PDSCHs of other DL CCs using the CIF(cross-scheduling). A PDCCH is not transmitted on DL CC B and DL CC C.

In next-generation RAT (Radio Access Technology), a self-containedsubframe is considered in order to minimize data transmission latency.FIG. 10 illustrates a self-contained subframe structure. In FIG. 10 , ahatched region represents a DL control region and a black regionrepresents a UL control region. A blank region may be used for DL datatransmission or UL data transmission. DL transmission and ULtransmission are sequentially performed in a single subframe, and thusDL data can be transmitted and UL ACK/NACK can also be received in asubframe. Consequently, a time taken until data retransmission isperformed when a data transmission error is generated is reduced andthus final data delivery latency can be minimized.

As examples of self-contained subframe types which can beconfigured/set, the following four subframe types can be considered.Respective periods are arranged in a time sequence.

-   -   DL control period+DL data period+GP (Guard Period)+UL control        period    -   DL control period+DL data period    -   DL control period+GP+UL data period+UL control period    -   DL control period+GP+UL data period

A PDFICH, a PHICH and a PDCCH can be transmitted in the data controlperiod and a PDSCH can be transmitted in the DL data period. A PUCCH canbe transmitted in the UL control period and a PUSCH can be transmittedin the UL data period. The GP provides a time gap in a process in whicha BS and a UE switch from a transmission mode to a reception mode or ina process in which the BS and the UE switch from the reception mode tothe transmission mode. Some OFDM symbols in a subframe at a time when DLswitches to UL may be set to the GP.

Embodiment: CA Scheme Between Different OFDM Numerologies

In 3GPP New RAT (NR) system environment, it may be able to differentlyconfigure OFDM numerology (e.g., subcarrier spacing and OFDM symbolduration based on the subcarrier spacing) among a plurality of cellscarrier aggregated on a signal UE. Hence, (absolute time) duration of atime resource configured by the same number of symbols (e.g., an SF, aslot, or a TTI (for clarity, commonly referred to as TU (Time Unit)) canbe differently configured between CA cells. In this case, a symbol caninclude an OFDM symbol and an SC-FDMA symbol.

FIG. 11 illustrates a frame structure defined in 3GPP NR. Similar to aradio frame structure of LTE/LTE-A (refer to FIGS. 2A and 2B), in 3GPPNR, a radio frame includes 10 subframes and each of the subframes has alength of 1 ms. A subframe includes one or more slots and a slot lengthvaries depending on an SCS. 3GPP NR supports SCS of 15 KHz, 30 KHz, 60KHz, 120 KHz, and 240 KHz. In this case, a slot corresponds to a TTIshown in FIG. 10 .

Table 4 illustrates a case that the number of symbols per slot, thenumber of slots per frame, and the number of slots per subframe varyaccording to an SCS.

TABLE 4 Number of Number of Number of symbols slot slot SCS(15*2{circumflex over ( )}u) within slot within frame within subframe 15KHz (u = 0) 14 10 1 30 KHz (u = 1) 14 20 2 60 KHz (u = 2) 14 40 4 120KHz (u = 3)  14 80 8 240 KHz (u = 4)  14 160 16

In consideration of this, when CA is performed on cells having adifferent SCS and OS duration, it may consider an operation methoddescribed in the following for a DL/UL data-related HARQ procedure(e.g., when DL/UL data transmission in an Scell is cross-CC scheduledfrom a Pcell, A/N feedback is transmitted via the Pcell in response toDL data received in the Scell.) When CA is performed on cells having thesame SCS and OS duration, although TU (e.g., slot) duration isdifferently configured between the cells, the same principle can beapplied.

In the following, the present invention is explained centering on a casethat a TU corresponds to a slot with reference to a frame structure ofNR. The TU can be defined by various time resource units depending on asystem. In the following description, a Pcell can be generalized by acell configured to transmit a PUCCH (hereinafter, a PUCCH cell). Forexample, the PUCCH cell may include a specific Scell (e.g., PrimarySecondary Cell (PSCell) configured to transmit a PUCCH. And, a Scell inwhich data is transmitted/received is generalized by a data cell or ascheduled cell and a cell in which grant DCI is transmitted can begeneralized by a control cell or a scheduling cell. And, a cell can bereplaced with a CC (Component Carrier). DCI is transmitted via PDCCH, ULdata is transmitted via PUSCH, and DL data can be transmitted via PDSCH.

(A) Cross-CC Scheduling Between Different SCS

FIG. 12 illustrates a case that a cell X having a big SCS (i.e., shortOS duration or short TU (e.g., slot) duration) is configured to bescheduled by a cell Y having a small SCS (i.e., long OS duration or longTU duration). Referring to FIG. 12 , DL/UL data transmission in the K(K>1) number of TUs of the cell X can be configured to be scheduled byone TU of the cell Y. In this case, a single TU of the cell Y and the K(e.g., multiple of 2) number of TUs of the cell X may have the same timeduration. Specifically, Opt 1) when a DL/UL grant for scheduling the(maximum) K number of TUs of the cell X is transmitted/detected at thesame time via a DL control channel transmission region (within a singleTU) of the cell Y or Opt 2) when the K number of DL control channeltransmission regions within a single TU of the cell Y is independentlyconfigured, it is able to transmit/detect a DL/UL grant for scheduling adifferent single TU in the cell X via each region. In this case, a TU tobe scheduled from among the K number of TUs of the cell X correspondingto single TU duration of the cell Y can be indicated via a DL/UL grant.

In the abovementioned methods (i.e., Opt 1), an operation ofsimultaneously detecting/receiving multiple DCIs can be differentlysupported according to parallel (decoding/encoding) processingcapability of UE implementation for a plurality of DL/UL data channels(and multiple PDCCHs on which DL/UL grant DCI scheduling the channels iscarried). For example, in case of a UE supporting a cross-CC schedulingoperation between a scheduling cell Y operating with a specific SCS anda scheduled cell X operating with an SCS greater than the specific SCSas much as K times, it is able to regulate UE capability/implementationto make the UE simultaneously detect/receive (and simultaneously performmaximum K number of DL (UL) data processing) (at least) maximum K numberof DL (UL) grant DCI via a DL control channel transmission/search(resource) region. As a different example, (under the cross-CCscheduling configuration), the maximum number of DL (UL) grant DCI(e.g., Lu) capable of being simultaneously detected/received via a DLcontrol channel transmission/search (resource) region may vary dependingon a UE implementation. In particular, a UE can report capability (i.e.,Lu value) of the UE related to the operation above to a base station. Asa further different example, (under the cross-CC schedulingconfiguration of FIG. 12 ), a UE can receive a configuration of themaximum number (e.g., Lc) of DL (UL) grant DCI capable of beingsimultaneously scheduled/transmitted from the base station (via a DLcontrol channel transmission/search (resource) region). Hence, the UEcan perform blind decoding by assuming a state that the UE is able todetect/receive the maximum Lc number of DL (UL) grant DCI at the sametime.

The abovementioned method/operation can be similarly applied to asituation that a self-CC scheduling is configured in a manner that DL/ULdata transmitted via a random cell is scheduled by DCI transmitted viathe cell itself (in a state that DL grant DCI-to-DL data timing (or ULgrant DCI-to-UL data timing) is dynamically indicated via DCI) or asituation that a cross-CC scheduling is configured between a scheduledcell X and a scheduling cell Y operating with the same SCS. For example,the maximum number of DL (UL) grant DCIs (e.g., Lu) capable of beingsimultaneously detected/received via a DL control channeltransmission/search (resource) region can be differentiated according toUE implementation. Hence, a UE can report capability (i.e., Lu value) ofthe UE related to the operation above to a base station. As a differentexample, a UE can receive a configuration of the maximum number (e.g.,Lc) of DL (UL) grant DCI capable of being simultaneouslyscheduled/transmitted from the base station (via a DL control channeltransmission/search (resource) region). Hence, the UE can perform blinddecoding by assuming a state that the UE is able to detect/receive themaximum Lc number of DL (UL) grant DCI at the same time.

Meanwhile, when a plurality of DL grant DCIs schedule a plurality ofdifferent DL data (e.g., PDSCH) transmitted on a single CC (e.g., dataCC), it is able to configure a plurality of the DL grant DCIs to betransmitted via the same slot (same control resource set or same PDCCHsearch space within the slot) within a specific CC (e.g., control CC).In this case, the control CC corresponds to a CC on which PDCCH ismonitored by a UE. The control CC can be configured to be identical to aCC (e.g., data CC) on which data transmission/reception is performedaccording to a cross-CC scheduling configuration. Or, the control CC canbe configured by a CC different from a data CC. Meanwhile, when DL datais transmitted via a specific CC to configure a dynamic HARQ-ACK payload(codebook), it may apply counter-DAI (and/or total-DAI) signaling toindicate a scheduling order of the DL data (on the basis of a CC index)(and/or the total number of scheduled DL data (until a current slot))via DL grant DCI. When a plurality of DL grant DCIs are transmitted inthe same slot (same control resource set or same PDCCH search spacewithin the slot) in response to a plurality of DL data transmitted onthe same data CC, it is necessary to have a reference for determining anorder/size of a counter-DAI value signaled by a plurality of the DCIs.To this end, it may consider a method of determining the counter-DAIvalue according to one of indexes described in the following (e.g., alow index is mapped to a small counter-DAI value).

-   -   1) CCE index    -   2) PDCCH candidate index used for transmitting DL grant DCI    -   3) PDCCH search space in which DL grant PDCCH is transmitted or        an index of a control resource set    -   4) Slot index (of data CC) at which DL data is transmitted    -   5) First or last symbol index allocated to transmit DL data    -   6) Index of DL data resource candidate (combined by slot        offset/starting symbol/duration) configured via RRC

FIG. 13 illustrates a case that a cell X having a small SCS (i.e., longOS duration or long TU duration) is configured to be scheduled by a cellY having a big SCS (i.e., short OS duration or short TU duration).Referring to FIG. 13 , DL/UL data transmission in a single TU of thecell X can be configured to be scheduled by all or a part (e.g., 1 TU)of the N (N>1) number of TUs of the cell Y. In this case, the N (e.g.,multiple of 2) number of TUs of the cell Y and a single TU of the cell Xmay have the same time duration (for clarity, N number of TUs of thecell Y aligned with the single TU of the cell X). Specifically, Opt 1) aDL/UL grant for scheduling a single TU of the cell X istransmitted/detected via a TU belonging to a plurality of TUs (i.e., TUgroup) corresponding to all or a part of the N number of TUs of the cellY (FIG. 13 (a)) or Opt 2) a DL/UL grant for scheduling a TU of the cellX can be transmitted/detected via a specific TU (e.g., a first TU amongthe N number of TUs or a TU of the cell Y overlapped with a first OSwithin a TU of the cell X over time) among the N number of TUs of thecell Y (FIG. 13 (b)).

In the abovementioned methods (i.e., Opt 1), an operation ofsimultaneously detecting/receiving DCI can be differently supportedaccording to buffering processing capability of UE implementation for aDL/UL data channel. For example, in case of a UE supporting a cross-CCscheduling operation between a scheduled cell X operating with aspecific SCS and a scheduling cell Y operating with an SCS greater thanthe specific SCS as much as K times, it is able to regulate UEcapability/implementation to make the UE detect/receive DL (UL) grantDCI (and perform buffering processing of DL data) scheduling a TU of thecell X via any TU among the N number of TUs of the cell Y aligned withthe TU of the cell X. As a different example, (under the cross-CCscheduling configuration illustrated in FIG. 13 ), TU timing (of thecell Y) capable of detecting/receiving DL (UL) grant DCI scheduling theTU of the cell X among the N number of TUs of the cell Y can bedifferentiated according to UE implementation. Hence, a UE can reportcapability (i.e., TU timing information of the cell Y capable ofdetecting/receiving DL (UL) grant DCI scheduling the TU of the cell X)of the UE related to the operation above to a base station. As a furtherdifferent example, (under the cross-CC scheduling configurationillustrated in FIG. 13 ), it is able to configure DL (UL) grant DCIscheduling the TU of the cell X to be detected/received via a TU (of thecell Y) equal to or faster than DL (UL) data starting symbol/timingtransmitted via the TU of the cell X only among the N number of TUs ofthe cell Y.

Meanwhile, in case of the Opt 1, TU timing at which a DL/UL grant istransmitted within a TU group may vary and each of a DL grant and a ULgrant can be transmitted via a different TU within the TU group. Hence,a UE can sequentially perform a blind decoding operation on DL controlchannel transmission regions of all TUs belonging to the TU group. Ifall DL/UL grants for the cell X are detected within a TU group of thecell Y, the UE may not perform the blind decoding operation on DLcontrol channel transmission regions within the remaining TUs. And, incase of the Opt 1, a DL control channel detection operation of a UE canbe performed in a manner that a BD count (e.g., Nb times) for a DLcontrol channel assigned by single TU scheduling of a cell X isdistributed to a plurality of TUs (e.g., Ns number of TUs) constructinga TU group of a cell Y (e.g., BD is performed (Nb/Ns) times in each TU).Meanwhile, according to the Opt 2, a specific TU transmitting a DL/ULgrant for the cell X among the N number of TUs of the cell Y can beconfigured via higher layer signaling (e.g., RRC signaling) or can beautomatically designated based on a predefined rule (e.g., a first TUamong the N number of TUs of the Y cell positioned at the same timing ofTU of the cell X).

Meanwhile, when a cell X having a long TU length is configured toperform cross-scheduling on a cell Y having a short TU length, sincescheduling (together with DL/UL grant DCI transmission) is performed ona plurality of TUs of the cell Y in a single TU of the cell X, DLcontrol resource burden can be increased. Hence, cross-CC scheduling canbe permitted only when a difference between a long TU length of the(scheduling) cell X and a short TU length of the (scheduled) cell Y isequal to or less than a specific level (e.g., when a TU of the cell X isequal to or less than a specific multiple of a TU of the cell Y). As adifferent method, it may consider a method of setting a limit on thenumber of cell Ys having a short TU configured to be cross-CC scheduledby a cell X having a long TU to make the number to be a value equal toor less than a specific value.

(B) HARQ-ACK Timing for CA with Different SCS

1) DL Data-to-HARQ-ACK

In the CA situation of 3GPP NR system, SCS or OS duration (or a TUlength) can be differently configured between a cell (e.g., Scell) inwhich DL data is transmitted and a cell (e.g., Pcell) in which A/Nfeedback is transmitted in response to the DL data. In this case, Opt1-1) A/N timing (e.g., delay between DL data reception and A/Ntransmission) can be configured on the basis of a TU length of the Scellin which the DL data is transmitted (e.g., A/N timing (candidate set) isconfigured by a multiple of S cell TU length) or Opt 1-2) the A/N timingcan be configured on the basis of a TU length of the Pcell in which theA/N feedback is transmitted (e.g., A/N timing (candidate set) isconfigured by a multiple of Pcell TU length). The Opt 1-1 can becomprehended as the A/N timing is configured on the basis of numerologyused for transmitting DL data (e.g., PDSCH transmission). The Opt 1-2can be comprehended as the A/N timing is configured on the basis ofnumerology used for performing A/N transmission (e.g., PUCCHtransmission). For clarity, A/N timing configured based on the Opt1-1/1-2 is referred to as temp A/N timing. In this case, information onthe A/N timing (e.g., Number of TUs) can be indicated via a DL grantthat schedules DL data.

First of all, in case of the Opt 1-1, actually applied actual A/N timingof the Pcell can be determined as an overlapped timing with a timingappearing after temp A/N timing (e.g., time corresponding to N number ofScell TUs) from the timing at which DL data is received on Scell, or anearliest TU (or UL control channel transmission (for A/N)) duration) onthe Pcell appearing on or after the overlapped timing. Specifically,when it is assumed that DL data is received at Scell TU #k, for Pcell TUlength<Scell TU length, a specific (e.g., first or last) Pcell TU #namong a plurality of Pcell TUs positioned at the same timing with ScellTU #(k+N) can be determined as actual A/N timing. In this case, amongthe a plurality of the Pcell TUs positioned at the same timing with theScell SF #(k+N), the Pcell TU #n corresponding to the actual A/N timingcan be configured via higher layer signaling (e.g., RRC signaling), canbe dynamically indicated via DL grant DCI, or can be automaticallydesignated based on a predefined rule (e.g., the first or the last TUamong a plurality of the Pcell TUs). In addition, when the number ofcandidate A/N timing types is indicated via a DL grant, DL data of Scellcan be configured to have less number of types compared to DL data ofPcell (e.g., when TU lengths of the two cells have a relationship of Ntimes, a value corresponding to 1/N). In this case, an interval betweencandidate A/N timings corresponding to DL data of each cell can beconfigured by the same value between the two cells.

On the contrary, for Pcell TU length>Scell TU length, a Pcell TU #npositioned at the same timing with Scell TU #(k+N) or a Pcell TU #(n+1)appearing immediately after the Pcell TU #n can be determined as actualHARQ timing. In this case, the Pcell TU #n or the Pcell TU #(n+1)corresponding to the actual A/N timing can be configured via higherlayer signaling (e.g., RRC signaling), can be dynamically indicated viaDL grant DCI, or can be automatically designated based on a predefinedrule, For example, if PUCCH transmission duration or the number ofsymbols is equal to or less than a specific value in Pcell, the Pcell TU#n is designated as the actual A/N timing. If the PUCCH transmissionduration or the number of symbols exceeds the specific value, the PcellTU #(n+1) is designated as the actual A/N timing. And/or, if an order ofScell TU #(k+N) is equal to or less than a specific value among aplurality of the Scell TUs, which is in the same time as the Pcell TU#n, the Pcell TU #n is designated as the actual A/N timing. If the orderof the Scell TU #(k+N) exceeds the specific value, the Pcell TU #(n+1)is designated as the actual A/N timing.

In addition, an interval (N) between candidate A/N timings capable ofbeing indicated via a DL grant can be configured, so that DL data ofScell has a longer interval compared to DL data of Pcell (e.g., when TUlengths of the two cells have a relationship of N times, a multiple ofN). In this case, the number of candidate A/N timings can be configuredby the same value between the two cells.

And, in case of the Opt 1-2, an actually applied actual A/N timing onPcell can be determined as TU (or (A/N) UL control channel transmission)duration appearing after temp A/N timing (e.g., time corresponding tothe M number of Pcell TUs) from an overlapped timing with DL datareception timing on Scell, or an earliest TU (or (A/N) UL controlchannel transmission) duration on Pcell existing on or after theoverlapped timing. Specifically, when it is assumed that DL datareception timing corresponds to Scell TU #n, for Pcell TU length<ScellTU length (i.e., Pcell SCS>Scell SCS), a Pcell TU #(k+M) can bedetermined as actual A/N timing on the basis of a specific Pcell TU #k(e.g., the first or the last) among a plurality of Pcell TUs positionedat the same timing with Scell TU #n. In the foregoing description, “aspecific Pcell TU #k (hereinafter, HARQ-ACK reference TU) among aplurality of Pcell TUs” can be configured via higher layer signaling(e.g., RRC signaling), can be dynamically indicated via DL grant DCI, orcan be designated based on a predefined rule (e.g., the first or thelast TU among a plurality of the Pcell TUs). On the contrary, for ‘PcellTU length>Scell TU length’ or ‘Pcell TU length=Scell TU length’ (i.e.,Pcell SCS<=Scell SCS), a Pcell TU #(k+M) can be determined as actual A/Ntiming on the basis of a Pcell TU #k positioned at the same timing withScell TU #n.

Meanwhile, when a cell X having a long TU length is configured totransmit A/N in response to DL data reception in a cell Y having a shortTU length (i.e., cross-CC UCI transmission), since it is necessary toperform multiple A/N transmissions (PUCCH transmission) in response tomultiple DL data in the cell Y in a single TU of the cell X, UL controlresource burden can be increased. Hence, cross-CC UCI transmission canbe permitted only when a difference between a long TU length of the (ULcontrol) cell X and a short TU length of the (DL data) cell Y is equalto or less than a specific level (e.g., when a TU of the cell X is equalto or less than a specific multiple of a TU of the cell Y). As adifferent method, it may consider a method of setting a limit on thenumber of cell Ys having a (DL data) short TU configured to transmit UCIvia the (UL control) cell X having a long TU to make the number to be avalue equal to or less than a specific value.

2) UL Grant DCI-to-UL Data

Meanwhile, in case of UL HARQ, SCS or OS duration (or a TU length) canbe differently configured between a cell (e.g., Pcell) in which a ULgrant is transmitted and a cell (e.g., Scell) in which UL data istransmitted in response to the UL grant. In this case, Opt 2-1) HARQtiming (e.g., delay between UL grant reception and UL data transmission)can be configured on the basis of a TU length (e.g., HARQ timing(candidate set) is configured by a multiple of a Pcell TU length) of theScell in which the UL grant is transmitted or Opt 2-2) the HARQ timingcan be configured on the basis of a TU length (e.g., HARQ timing(candidate set) is configured by a multiple of a Scell TU length) of theScell in which the UL data is transmitted. The Opt 2-1 can becomprehended as the HARQ timing is configured on the basis of numerologyused for transmitting UL grant (e.g., PDCCH transmission). The Opt 2-2can be comprehended as the HARQ timing is configured on the basis ofnumerology used for performing UL data transmission (e.g., PUSCHtransmission). For clarity, HARQ timing configured based on the Opt2-1/2-2 is referred to as temp HARQ timing. In this case, information onthe HARQ timing (e.g., number of TUs) can be indicated via a UL grant.

First of all, in case of the Opt 2-1, actually applied actual HARQtiming on the Scell can be determined by an overlapped timing withtiming appearing after temp HARQ timing (e.g., time corresponding to Knumber of Pcell TUs) from the timing at which a UL grant is received onPcell, or an earliest TU (or UL data channel transmission) on the Scellappearing on or after the overlapped timing.

Meanwhile, in case of the Opt 2-2, actually applied actual HARQ timingon Scell can be determined as TU (or UL data channel transmission)duration appearing after temp HARQ timing (e.g., time corresponding tothe L number of Scell TUs) from an overlapped timing with the UL grantreception timing on Pcell, or an earliest TU (or UL data channeltransmission) duration on Scell existing on or after the overlappedtiming. Specifically, when it is assumed that UL grant reception timingcorresponds to Pcell TU #n, for Pcell TU length>Scell TU length (i.e.,Pcell SCS<Scell SCS), a Scell TU #(k+L) can be determined as actual HARQtiming on the basis of a specific Scell TU #k (e.g., the first or thelast) among a plurality of Scell TUs positioned at the same timing withPcell TU #n. In the foregoing description, “a specific Scell TU #k(hereinafter, UL-HARQ reference TU) among a plurality of Scell TUs” canbe configured via higher layer signaling (e.g., RRC signaling), can bedynamically indicated via UL grant DCI, or can be designated based on apredefined rule (e.g., the first or the last TU among a plurality of theScell TUs). On the contrary, if for ‘Pcell TU length<Scell TU length’ or‘Pcell TU length=Scell TU length’ (i.e., Pcell SCS>=Scell SCS), a ScellTU #(k+L) can be determined as actual HARQ timing on the basis of aScell TU #k positioned at the same timing with Pcell TU #n.

3) DL Grant DCI-to-DL Data

Meanwhile, in case of DL HARQ, SCS or OS duration (or a TU length) canbe differently configured between a cell (e.g., Pcell) in which a DLgrant is transmitted and a cell (e.g., Scell) in which DL data istransmitted in response to the DL grant. In this case, Opt 3-1) HARQtiming (e.g., delay between DL grant reception and DL data transmission)can be configured on the basis of a TU length (e.g., HARQ timing(candidate set) is configured by a multiple of a Pcell TU length) of thePcell in which the DL grant is transmitted or Opt 3-2) the HARQ timingcan be configured on the basis of a TU length (e.g., HARQ timing(candidate set) is configured by a multiple of a Scell TU length) of theScell in which the DL data is transmitted. The Opt 3-1 can becomprehended as the HARQ timing is configured on the basis of numerologyused for transmitting DL grant (e.g., PDCCH transmission). The Opt 3-2can be comprehended as the HARQ timing is configured on the basis ofnumerology used for performing DL data transmission (e.g., PDSCHtransmission). For clarity, HARQ timing configured based on the Opt3-1/3-2 is referred to as temp HARQ timing. In this case, information onthe HARQ timing (e.g., number of TUs) can be indicated via a DL grant.

First of all, in case of the Opt 3-1, actually applied actual HARQtiming of the Scell can be determined as an overlapped timing overlappedwith timing appearing after temp HARQ timing (e.g., time correspondingto K number of Pcell TUs) from the timing at which a DL grant isreceived on Pcell, or an earliest TU (or DL data channel transmission)on the Scell appearing after the overlapped timing.

Meanwhile, in case of the Opt 3-2, actually applied actual HARQ timingon Scell can be determined as TU (or DL data channel transmission)duration appearing after temp HARQ timing (e.g., time corresponding tothe L number of Scell TUs) from a overlapped timing with the DL grantreception timing on Pcell, or an earliest TU (or DL data channeltransmission) duration on Scell existing on or after the overlappedtiming. Specifically, when it is assumed that DL grant reception timingcorresponds to Pcell TU #n, for Pcell TU length>Scell TU length issatisfied (i.e., Pcell SCS<Scell SCS), a Scell TU #(k+L) can bedetermined as actual HARQ timing on the basis of a specific Scell TU #k(e.g., the first or the last) among a plurality of Scell TUs positionedat the same timing with Pcell TU #n. In the foregoing description, “aspecific Scell TU #k (hereinafter, DL-HARQ reference TU) among aplurality of Scell TUs” can be configured via higher layer signaling(e.g., RRC signaling), can be dynamically indicated via DL grant DCI, orcan be designated based on a predefined rule (e.g., the first or thelast TU among a plurality of the Scell TUs). On the contrary, for ‘PcellTU length<Scell TU length’ or ‘Pcell TU length=Scell TU length’ (i.e.,Pcell SCS>=Scell SCS), a Scell TU #(k+L) can be determined as actualHARQ timing on the basis of a Scell TU #k positioned at the same timingwith Pcell TU #n.

Preferably, in the Opt 1-2, “the specific Pcell TU #k among a pluralityof the Pcell TUs” for the HARQ-ACK reference TU can be configured as thelast TU among a plurality of the Pcell TUs. In order to transmit A/Nafter DL data is received, certain amount of processing time isnecessary. For example, if the HARQ-ACK reference TU is designated asthe first TU among a plurality of Pcell TUs, it is unable to transmitA/N in the HARQ-ACK reference TU. Hence, if information on A/N timing isindicated via DL grant DCI, information indicating a specific TU (e.g.,a TU positioned between the HARQ-ACK reference TU and a TU withinprocessing time necessary for transmitting A/N) is not valid. Hence,since it is unable to use a part of the information on the A/N timing,signaling information is restricted. For example, if the A/N timing isdefined by a TU offset having values ranging from 0 to N−1, it is unableto use values ranging from 0 to L−1 (L<N) for signaling. And, since alength of a slot is variously provided according to SCS, the number (L)of TUs within processing time necessary for transmitting A/N varies. Asa result, signaling information is restricted and system complexity canbe increased.

FIG. 14 illustrates signal transmission according to the option 1-2.Referring to FIG. 14 , DL data is received in a slot #n of a cell X(SCS: × KHz). If the cell X is not a PUCCH cell (e.g., Pcell), it may beable to transmit A/N in a PUCCH cell (e.g., cell Y) in response to theDL data. In this case, since SCS of the cell Y corresponds to 4× KHz,the slot #n of the cell X corresponds/is aligned to/with 4 slots of thecell Y (e.g., slot #p to slot #p+3) and A/N for the DL data can betransmitted after k slots (e.g., 4 slots) on the basis of the last slot(i.e., slot #p+3) among the 4 slots of the cell Y corresponding to theslot #n of the cell X. Information on k can be indicated via controlinformation (e.g., DL grant DCI) that schedules the DL data. In thiscase, the k may correspond to an integer equal to or greater than 0. Thek is configured based on numerology used for transmitting A/N (e.g.,PUCCH transmission). In this case, the DL data and the DL grant DCI canbe received via PDSCH and PDCCH, respectively. In this case, asdescribed later, a cell can be replaced with a subband.

In the option 2-2, a specific Scell TU #k for a UL-HARQ reference TU canbe configured by the last TU among a plurality of Scell TUs or can beconfigured by one of a plurality of the Scell TUs via higher layersignaling (e.g., RRC signaling). In order to transmit UL data after ULgrant DCI is received, a certain amount of processing time is necessary.In particular, similar to HARQ-ACK reference TU, the UL-HARQ referenceTU can be designated by the last TU among a plurality of the Scell TUs.Meanwhile, in order to maintain unity between UL data processing and DLdata processing, similar to DL-HARQ reference TU described later, theUL-HARQ reference TU can be designated by the first TU among a pluralityof the Scell TUs.

FIG. 15 illustrates signal transmission according to the option 2-2.Referring to FIG. 15 , UL grant DCI is received in a slot #n of a cell X(SCS: × KHz) and UL data can be transmitted in a cell Y (SCS: 4× KHz).In this case, since SCS of the cell Y corresponds to 4× KHz, the slot #nof the cell X corresponds/is aligned to/with 4 slots of the cell Y(e.g., slot #p to slot #p+3) and the UL data can be transmitted after kslots (e.g., 4 slots) on the basis of the last slot (i.e., slot #p+3)among the 4 slots of the cell Y corresponding to the slot #n of the cellX (option 1) or can be transmitted after k (e.g., 7) slots on the basisof the first slot (i.e., slot #p) (option 2). Information on k can beindicated via UL grant DCI. In this case, the k may correspond to aninteger equal to or greater than 0. The k is configured based onnumerology used for transmitting UL data (e.g., PUSCH transmission). Inthis case, the UL data can be transmitted via PUSCH and the UL grant DCIcan be received via PDCCH. In this case, as described later, a cell canbe replaced with a subband.

In the option 3-2, a specific Scell TU #k for a DL-HARQ reference TU canbe configured by the first TU among a plurality of Scell TUs. Since itis able to receive DL grant DCI and DL data at the same time, ifHARQ-ACK reference TU is designated by the first TU among a plurality ofthe Scell TUs, it is able to increase a use efficiency of a DL datatransmission resource.

FIG. 16 illustrates signal transmission according to the option 3-2.Referring to FIG. 16 , DL grant DCI is received in a slot #n of a cell X(SCS: × KHz) and DL data can be transmitted in a cell Y (SCS: 4× KHz).In this case, since SCS of the cell Y corresponds to 4× KHz, the slot #nof the cell X corresponds/is aligned to/with 4 slots of the cell Y(e.g., slot #p to slot #p+3) and the DL data can be received after kslots (e.g., 2 slots) on the basis of the first slot (i.e., slot #p)among the 4 slots of the cell Y corresponding to the slot #n of the cellX. Information on k can be indicated via DL grant DCI. In this case, thek may correspond to an integer equal to or greater than 0. The k isconfigured based on numerology used for transmitting DL data (e.g.,PDSCH transmission). In this case, the DL data can be received via PDSCHand the DL grant DCI can be received via PDCCH. In this case, asdescribed later, a cell can be replaced with a subband.

Meanwhile, when a single cell or a carrier is divided into a pluralityof subbands and an SCS or a TU of a different size is set to each of aplurality of the subbands, although a UE operates on a plurality of thesubbands at the same time or switches between subbands, the proposedmethods of the present invention can be similarly applied. In this case,a cell can be replaced with a subband (within a cell) in the presentinvention. In this case, the subband is configured by contiguousfrequency resources (e.g., a plurality of contiguous RBs) and can bereferred to as a BWP (bandwidth part).

FIG. 17 illustrates a BS and a UE of a wireless communication system,which are applicable to embodiments of the present invention.

Referring to FIG. 17 , the wireless communication system includes a BS110 and a UE 120. When the wireless communication system includes arelay, the BS or UE may be replaced by the relay.

The BS 110 includes a processor 112, a memory 114 and a radio frequency(RF) unit 116. The processor 112 may be configured to implement theprocedures and/or methods proposed by the present invention. The memory114 is connected to the processor 112 and stores information related tooperations of the processor 112. The RF unit 116 is connected to theprocessor 112 and transmits and/or receives an RF signal. The UE 120includes a processor 122, a memory 124 and an RF unit 126. The processor122 may be configured to implement the procedures and/or methodsproposed by the present invention. The memory 124 is connected to theprocessor 122 and stores information related to operations of theprocessor 122. The RF unit 126 is connected to the processor 122 andtransmits and/or receives an RF signal.

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It will beobvious to those skilled in the art that claims that are not explicitlycited in each other in the appended claims may be presented incombination as an embodiment of the present invention or included as anew claim by a subsequent amendment after the application is filed.

In the embodiments of the present invention, a description is madecentering on a data transmission and reception relationship among a BS,a relay, and an MS. In some cases, a specific operation described asperformed by the BS may be performed by an upper node of the BS. Namely,it is apparent that, in a network comprised of a plurality of networknodes including a BS, various operations performed for communicationwith an MS may be performed by the BS, or network nodes other than theBS. The term ‘BS’ may be replaced with the term ‘fixed station’, ‘NodeB’, ‘enhanced Node B (eNode B or eNB)’, ‘access point’, etc. The term‘UE’ may be replaced with the term ‘Mobile Station (MS)’, ‘MobileSubscriber Station (MS S)’, ‘mobile terminal’, etc.

The embodiments of the present invention may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the methods according to theembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the embodiments of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. For example, software code may be stored in a memory unitand executed by a processor. The memory unit is located at the interioror exterior of the processor and may transmit and receive data to andfrom the processor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

The present invention is applicable to UEs, eNBs or other apparatuses ofa wireless mobile communication system.

What is claimed is:
 1. A method of performing communication by a userequipment (UE) in a wireless communication system, the methodcomprising: receiving, based on physical downlink control channels(PDCCH)-monitoring, each downlink control information (DCI) configuredwith a counter-downlink assignment index (C-DAI) for downlink (DL)scheduling; performing, in at least one serving cell, a reception ofeach DL signal based on the reception of each DCI; and transmitting anAcknowledgement/Negative acknowledgement (A/N) codebook including A/Ninformation for the reception of each DL signal, wherein a value of theC-DAI denotes an accumulated number that is counted based on a servingcell index for the reception of each DL signal, and wherein, for aplurality of DL signal receptions in a same serving cell that arescheduled from a same time resource for the PDCCH-monitoring: each C-DAIvalue of each DCI is determined based on an increasing order of a DLsignal reception starting time.
 2. The method of claim 1, wherein theaccumulated number for the C-DAI is counted up to a current timeresource for the PDCCH-monitoring.
 3. The method of claim 1, wherein theaccumulated number for the C-DAI is counted in ascending order of eachserving cell index.
 4. The method of claim 1, wherein the accumulatednumber for the C-DAI is counted in ascending order of a time resourceindex for the PDCCH-monitoring.
 5. The method of claim 1, wherein theaccumulated number for the C-DAI is counted in ascending order of a timeresource index for the PDCCH-monitoring, after counting the accumulatednumber for the C-DAI in ascending order of each serving cell index. 6.The method of claim 1, wherein each DCI is configured with a total-DAIin addition to the C-DAI, and wherein a value of the total-DAI denotesan accumulated total number that is counted based on each serving cellindex for the reception of each DL signal, and a time resource index upto a current time resource for the PDCCH-monitoring.
 7. The method ofclaim 1, wherein the A/N codebook is configured as a dynamic A/Ncodebook.
 8. The method of claim 1, wherein the wireless communicationsystem contains 3rd Generation Partnership Project (3GPP)-based wirelesscommunication system.
 9. A non-transitory medium storing instructionsfor a user equipment (UE) to perform the method of claim
 1. 10. A methodof performing communication by a base station (BS) in a wirelesscommunication system, the method comprising: transmitting, to a userequipment (UE) through one or more physical downlink control channels(PDCCHs), each downlink control information (DCI) configured with acounter-downlink assignment index (C-DAI) for downlink (DL) scheduling;performing, in at least one serving cell, a transmission of each DLsignal as scheduled based on the transmission of each DCI; andreceiving, from the UE, an Acknowledgement/Negative acknowledgement(A/N) codebook including A/N information for the transmission of each DLsignal, wherein a value of the C-DAI denotes an accumulated number thatis counted based on a serving cell index for the transmission of each DLsignal, and wherein, for a plurality of DL signal transmissions in asame serving cell that are scheduled from a same time resource for thePDCCH-monitoring at the UE: each C-DAI value of each DCI is determinedbased on an increasing order of a DL signal transmission starting time.11. The method of claim 10, wherein the accumulated number for the C-DAIis counted up to a current time resource for the PDCCH-monitoring at theUE.
 12. The method of claim 10, wherein the accumulated number for theC-DAI is counted in ascending order of each serving cell index.
 13. Themethod of claim 10, wherein the accumulated number for the C-DAI iscounted in ascending order of a time resource index for thePDCCH-monitoring at the UE.
 14. The method of claim 10, wherein theaccumulated number for the C-DAI is counted in ascending order of a timeresource index for the PDCCH-monitoring at the UE, after counting theaccumulated number for the C-DAI in ascending order of each serving cellindex.
 15. The method of claim 10, wherein each DCI is configured with atotal-DAI in addition to the C-DAI, and wherein a value of the total-DAIdenotes an accumulated total number that is counted based on eachserving cell index for the transmission of each DL signal, and a timeresource index up to a current time resource for the PDCCH-monitoring atthe UE.
 16. The method of claim 10, wherein the A/N codebook isconfigured as a dynamic A/N codebook.
 17. A device for wirelesscommunication, the device comprising: a memory configured to storeinstructions; and a processor configured to perform operations byexecuting the instructions, the operations comprising: receiving, basedon physical downlink control channels (PDCCH)-monitoring, each downlinkcontrol information (DCI) configured with a counter-downlink assignmentindex (C-DAI) for downlink (DL) scheduling; performing, in at least oneserving cell, a reception of each DL signal based on the reception ofeach DCI; and transmitting an Acknowledgement/Negative acknowledgement(A/N) codebook including A/N information for the reception of each DLsignal, wherein a value of the C-DAI denotes an accumulated number thatis counted based on a serving cell index for the reception of each DLsignal, and wherein, for a plurality of DL signal receptions in a sameserving cell that are scheduled from a same time resource for thePDCCH-monitoring: each C-DAI value of each DCI is determined based on anincreasing order of a DL signal reception starting time.
 18. The deviceof claim 17, further comprising: a Radio Frequency module.
 19. Thedevice of claim 17, wherein the device is a user equipment (UE).
 20. Abase station (BS) for wireless communication, the BS comprising: atransceiver; and a processor configured to control the transceiver to:transmit, to a user equipment (UE) through one or more physical downlinkcontrol channels (PDCCHs), each downlink control information (DCI)configured with a counter-downlink assignment index (C-DAI) for downlink(DL) scheduling; perform, in at least one serving cell, a transmissionof each DL signal as scheduled based on the transmission of each DCI;and receive, from the UE, an Acknowledgement/Negative acknowledgement(A/N) codebook including A/N information for the transmission of each DLsignal, wherein a value of the C-DAI denotes an accumulated number thatis counted based on a serving cell index for the transmission of each DLsignal, and wherein, for a plurality of DL signal transmissions in asame serving cell that are scheduled from a same time resource for thePDCCH-monitoring at the UE: each C-DAI value of each DCI is determinedbased on an increasing order of a DL signal transmission starting time.